It is commonly known to use various designs of sprinklers and irrigation systems for various watering applications. Each of these applications typically requires consideration of an emission or flow rate for water distributed to the area, and a distance or area over which the water from a particular sprinkler is distributed. Some particularized applications for sprinkler and irrigations systems require further consideration.
As an example, watering golf courses requires consideration of a greater set of factors. Each of the sprinklers presents an unnatural obstacle that is preferably out of an area of normal play. That is, sprinklers are permanently located at various locations around a golf course. These locations are selected so that, in the normal course of play, most golf balls will avoid the sprinklers and covers placed thereover. As an irrigation network, of which the sprinklers are a part of, may be damaged by excessive weight being placed on the covers, the sprinkler locations are also selected to reduce the likelihood that golf carts are driven over them, as well as pedestrian or golf traffic in general.
Toward the same goal of allowing the sprinkler to be generally avoided by the patrons of a golf course, the number of sprinklers is selected to minimize their number and intrusiveness. However, a typical 18-hole golf course has fairways cumulatively totaling 7000 yards of linear distance or more, not to mention the breadth of the fairways, and areas bounding the fairways commonly known as the rough.
Covering the length and breadth requires distributing or throwing the water a sufficient distance from the sprinklers balanced against minimizing the number of sprinklers. The sprinklers are necessary to provide watering to a variety of verdure, flora and fauna, grass, trees and shrubs, ranging from the azaleas and dogwood trees of Augusta National golf course to the prickly gorse of The Old Course in St. Andrews, Scotland. Watering golf courses, and in particular the watering of fairways, has been performed with sprinklers directing water with a standard trajectory in the range of 20 to 30 degrees above horizontal, and the water is commonly distributed distances of 60 to 100 feet.
While irrigating a farm crop area, the land is generally clear of anything other than the crops. With golf courses, it is common to have trees spread around in an irregular manner, the trees having low-hanging branches. It is also common for golf courses to include other overhanging obstructions. To avoid these obstructions on a golf course, as described, a trajectory lower than the standard trajectory may be used. However, this shortens the distance to which the water can be distributed from the sprinklers. Shortening the distance, then, requires a greater number of sprinklers.
In order to lower the trajectory without increasing the number of sprinklers, a greater throw distance is required. To do so, the water pressure and flow may be increased. Though a higher velocity at the sprinkler nozzle exit is produced, in practice the stream tends to break apart and cause misting, resulting in an imprecise water stream distributed from the sprinkler.
Another issue with golf courses is the careful regulation of the water quantity distributed and the moisture of the various areas. These areas include the fairways, the rough, out-of-bounds, patches of trees or plants, and high and low-lying areas that are affected by run-off more predominantly than other areas. As the areas of a golf course can vary so widely, the irrigation needs of each individual area is specifically planned. Sprinklers are on timers, or automatic sensors may govern the activation and de-activation of various sprinklers.
Nature itself often attempts to wreak havoc on the carefully-designed watering plans. For the most part, the watering plans can be adjusted to compensate for these attempts. Unfortunately, wind is one condition for which it is difficult to plan or compensate. The golf course at Torrey Pines in San Diego, Calif., is located on a bluff overlooking the Pacific Ocean, while the Old Course in St. Andrews is across a beach from the North Sea. Each of these settings subjects their golf courses to a wide range of wind conditions.
Strong winds have a number of negative effects on watering from irrigation sprinklers. In all cases, the wind directs water streams propelled through the air in a downwind direction. In some cases, this results in inappropriate areas receiving water from the stream. In the upwind direction, the stream is unable to distribute water to the proper distances. A water stream under higher pressures, and thus more prone to misting into smaller water droplets, is also more susceptible to effects from the wind as there is an increase in the ratio of wind force on the surface of the droplets and the mass of the droplets.
A lower trajectory for the water stream is less susceptible to wind effects. Wind composed of air, like any other fluid flow, obeys what is known as the no-slip boundary condition. Therefore, the speed or velocity of the wind tends to be lower near the ground surface. In addition, ground structures such as buildings, fences, and trees, reduces the effects of wind close to the ground level.
In summary, there are a number of carefully considered balances in golf course irrigation. A high trajectory for the water stream allows greater distribution distance, but the stream is more susceptible to winds and may be interfered with by trees, for instance, located on the golf course, and a lower trajectory avoiding such obstacles reduces the distribution distance. While a higher-pressured water source may help increase distribution distance, the stream is, again, more susceptible to wind. The number of sprinklers may be increased, but a greater number of sprinklers means a greater number of obstacles to the golf course which can impact or affect the enjoyment of the course by golfers.
Accordingly, there has been a need for an improved sprinkler for efficiently irrigating golf courses or other like areas.